1. Technical Field
The present invention relates to a liquid ejecting head for an ink jet type recording head or the like which applies a pressure change to a pressure generating chamber, communicating with nozzles, to eject from the nozzles a liquid in the pressure generating chamber.
2. Related Art
Examples of liquid ejecting heads which generate a pressure change in a liquid in a pressure generating chamber to eject the liquid as liquid droplets from nozzles include an ink jet type recording head (hereinafter simply referred to as “recording head”) used in an image recording apparatus such as an ink jet type recording apparatus (hereinafter simply referred to as “printer”), a color material ejecting head used to manufacture a color filter for a liquid crystal display or the like, an electrode material ejecting head used to form an electrode of an organic EL (Electro Luminescence) display, an FED (Field Emission Display) or the like, and a bioorganic material ejecting head used to manufacture a biochip (biochemical element).
For example, some of the recording heads are configured by mounting a flow path unit in which a series of liquid flow paths extending from a reservoir to a nozzle via a pressure generating chamber are formed, an actuator unit having a pressure generating element capable of varying the volume of the pressure generating chamber, and the like to a head case made of a resin. The flow path unit is connected with a nozzle plate having a plurality of nozzles provided therein.
A liquid to be ejected from such a recording head has a viscosity suitable for ejection, e.g., approximately 4 mPa·s, at normal temperature. The viscosity of a liquid correlates with the temperature such that the lower the temperature, the higher the viscosity, and the higher the temperature, the lower the viscosity. There is a case where a recording head is used to eject a liquid in a so-called high-viscosity region of 8 mPa·s or greater at normal temperature, such as an ultraviolet curable ink. Accordingly, there is a recording head provided with a heater to heat a liquid so that the viscosity of the liquid to be ejected from each nozzle becomes a uniform value suitable for ejection of the liquid regardless of the environmental temperature. A known example of such a heater is a thin sheet-like heater having a heating element folded back multiple times in a wavy wire. In addition, there has been proposed a heater which varies the amount of heat generated by making the layout pitch of portions of the heating element located in the center portion of the recording head wider than the layout pitch of portions of the heating element located at both ends of the recording head in order to uniformly heat the ink in the recording head (for example, refer to JP-A-2005-081597).